Colorectal cancer remains the second leading cause of cancer death in the United States. Recent advances in adjuvant therapy are just beginning to impact the 5-year survival rates. As a result, early detection and especially dietary and novel chemopreventive strategies represent the best hope to significantly decrease the mortality rates for this disease. Adherence to clinical trials is an area of increasing concern due in part to the cost involved in conducting community based clinical trials. There is increasing interest in identifying those factors that may affect adherence and are amenable to change, as well as developing methods to enhance adherence in clinical trials. There is evidence showing that adherence to long term clinical trials is achievable. However, the complexity of maintaining long term changes, particularly dietary changes should be recognized. The Adherence Core is a service resource which pools expertise and materials to support the three projects. Subjects in these clinical studies are 40-80 years old with a history of colorectal adenomatous polyps. The aims of the core are: 1. to monitor and evaluate adherence to study procedures, 2. to provide the nurse interveners with guidelines, consulting and training on promoting participant adherence to study protocols, 3. to develop strategies to reduce barriers associated with adherence problems in clinical trials, 4. to develop and produce materials (e.g. newsletters) and implement procedures (e.g. general adherence intervention) to enhance participant adherence to study procedures, 5. to develop, produce and distribute various written materials educating the participants about potential side effects and ways to manage them, 6. to optimize subject recruitment strategies to reduce attrition, 7. to develop instruments to identify behavioral factors that may influence/predict attrition and/or adherence, and 8. to educate participants about cancer, its etiology and prevention, with particular emphasis on colon cancer. Core outcomes include promotion of adherence, evaluation of the effectiveness of the General Adherence Enhancement intervention, the Problem-Solving remedial intervention for non-adherers, the Attrition Prevention intervention, and generation of qualitative data on problems experienced by participants in large clinical trials, as well as methods to solve them.